Lifting-jack.



LIFTING JAOK. LPPLIUATION FILED 10mm, 1910.

Patented Mar. 7, 1911.

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W. P. RIGHTMIRE.

LIFTING J AOK.

APPLIUATIQ! rILnn Nov. zn. 1910.

986,408. Patented um, 1911.-

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W. F. RIGHTMIRE.

LIPTING JACK;

APPLIOATION FILED NOV. 22, 1910.

Patented Mar. 7, 1911.

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UNITED STATES PATENT OFFICE.

WILLIAM F. RIGI-ITIVIIRE, OF TOPEKA, ICANSAS, ASSIGNOR OF ONE-HALF T0 NATHANIEL T. FOSTER, OF ROMNA, OKLAHOMA.

LIFTINGJ ACK.

Specification of Letters Patent.

Patented Mar. 7, 1911.

Application filed November 22, 1910. Serial No. 593,617.

To all whom it may concern.

Be it known that I, WILLIAM F. RIGHT- Mmn, a citizen of the United States, residing at Topeka, in the county of Shawnee and State of Kansas, have invented cert-ain new and useful Improvements in Lifting-Jacks, of which the following is a specification.

My invention relates to lifting aclrs compri'sing one or more standards and a lifting bar, with a rack and pawl mechanism operated by a lever for raising the lifting bar in the standards.

The object of my invention is to improve generally upon such lifting jacks; also to provide a simple, etlicient, strong, durable, and powerful lifting jack of this nature, that has a wide range of usefulness, is easy to operate in lifting heavy loads, and that is convenient in operation in lowering the lifting bar; also to construct a lifting jack, simple in construction, that will combine great power with ease of operation, in which the upward as well as the downward stroke of the lever is utilized in raising the lifting bar, as well as a lifting jack provided with a tripping lever by which the load can be lowered step by step, and by which the load or the lifting bar alone can be dropped to the bottom. And my invention comprises the parts, improvements, and combinations hereinafter set forth and claimed.

In the drawings accompanying and forming part of this specification, and inthe description of the drawings, I have shown my invention in its preferred form, and have shown what I deem to be the best mode of applying the principles thereof; but it is to be understood that my invention is not confined to the exact details of construction therein set forth, and that, within the scope of the appended claims, I contemplate changes in form, proportions, and materials, the transposition-of parts, and the substitution of equivalent members, without departing from the spirit of my invention.

Figure 1 is a vertical sectional elevation of a lifting jack made in accordance with the principles of my invention, taken on a plane approximately through the center line vfrom front to back. Fig. 2 is a side elevation, showing in dotted outlines, the positions of certain arts when the pawls are released to permit the lifting bar to drop to the bottom. Fig. 3 is an elevation taken from the rear, or lever, side, the lever being sh-own in section.

Similar reference characters indicate like or corresponding parts throughout the several views.

t is a bed-plate on which is erected a standard in two parts 5, 5, which are spaced apart from each other, as sho-wn at 6 to form a guide or way for the liftingbar 13. In the outer face of each part of the standard is formed a rack 7, the notches extending preferably only part way across said face, the remaining portion, 8, giving strength to the standard. Each rack is slotted, as shown at 9, from top to bottom, for purposes hereinafter explained. The parts of the standard may be properly secured together by means of lugs 10 at the bottom and 11 at the top, and the two parts o-f each rack may be held rigid at the top by means of the bolts 12, 12. In the lower portion of the lifting-bar is a slot 14, and the three slots are in alinement with each otheinf-L. 'l''iissthe main lever, or power lever, extending through I engagement with the rack on each side of theslot. Each pawl has an opening 20 at the top where it is pivoted to the mai-n lever, and also an opening 21 at the bottom.

22 is an extension spring secured at opposite ends to the lugs 23, 23 respectively on each pawl, and extending through-the slots 14, 9, 9, and the openings 21, 21, the purpose of t-he spring being to pull the pawls into engagement with the notches of the rack and to hold them there.

24 is a lift at the' top of the lifting-bar.; 25 and 26 are lifts, each comprising a web or brace portion 28 and a step'29, the brace portion extending out through the slot 9; and 27 is a. lift secured to the lifting-bar and having its web or brace portion extending out through the way. These lifts may be arranged at any desired locationson the lifting-bar, so they do not interfere with the working parts; but the manner of distributing them is suggested as a very convenient one for adapting the jack to a wide range of work.

It will readily be understood, from the foregoing descril'ition, that the lifting-bar is raised by working the main lover up and down, the load being carried by the two pawls alternately, the spring permitting the pawls to slide upwardly on that side of the main pivot which is raised, and to pull them into the notches, the one spring acting thus on both pawls. Preferably I employ two an tifriction rollers 30, 3() in the lifting-bar, at its bottom, which bear againstl the standards, and two, 31, 31, at the top of the standard, which bear against the liftingbar.

32 is'a rock-shaft loosely secured in the lower end of the pawl 19, and to the outer' ends of the rockshaftv are rigidly secured the two links 38, 34, one of which is provided with an operating lever 35. 36 is a rod secured to the links, and space-d apart from and parallel with the rock-shaft, and to this rod is pivoted a link 37, which passes through the slots 9, 9, and 14, and into the opening 21 of the other pawl, 18, where it is provided with a slot 38 which engages with the rod or pin 39 in said pawl. The parts described in this paragraph have nothing to do with the lifting of the liftingbar; nor, on the other hand, do they inter fere therewith, as the slot and pin connection at. 38, 39 permits the pawls to work freely as heretofore described. It is the purpose of this mechanism to disengage either or both pawls from the rack or racks, so as to permit the lifting-,bar to be lowered, either step by step, or all at once as by releasing both pawls. Both pawls may be released at once by turning the lever 35 so that the rod 36 bears against the outer face of the standard, in which position the pawl 19 is pushed to the left, and the pawl 18 to the right, the positions of some of the parts involved in such operation being indicated in dotted outlines in Fig. 2, and being indicated by their own respective numerals followed by a prime mark, thus 37, 18 36', 19', 35. There being nothing to hold the lifting-bar it will drop instantly to the bottom. By pushing the tripping lever back again, the jack is again ready for the lifting operation, the spring serving to hold all parts normally in position for lifting. To let down the lifting bar step by step, that is, to release either pawl without releasing the other, the main lever is operated to throw most or all of the weight on the pawl to be retained, and the tripping lever is shoved to the left to release the other pawl, when the main lever on the side of the ,freed pawl .may be lowered one or more notches; then the weight is shifted to this pawl, and the other pawl is released; etc.

What I claim is:

1. The combination of a bedplate; a standard erected thereon and comprising two parts spaced apart from each other to form a guide-way for a lifting-bar, and each part having a rack formed in its outer face, and a vertical slot extending through said part form top to bottom, the two slots registering with each other; a lifting-bar adapted to move vertically in the guideway and having an opening therethrough registerin r with said slots, a lift at the top of said lifting-bar, a lift secured thereto and extending through one of said slots, and a lift secured thereto and extending through the guide-way; a main lever extending through said slots and pivoted to the lifting-bar; a pawl opposite each rack and adapted to engage therewith and pivoted to the main lever, and each being adapted to span the slot and make full engagement with the rack on each side of the slot; an extension spring secured at opposite ends to the respective pawls, and extending through said opening and said slots; a rock-shaft working freely in the lower end of one of said pawls, a link secured to each end of said rocleshaft, one of said links being provided with an operating handle, a rod extending between said links spaced apart from and parallel' with said rock-shaft, a link pivoted to said rod and provided with a slot and extending through said opening and said slots in the racks, and a pin in the other pawl engaging said slot in the link.

2. The combination of a. standard oomp-rising two parts spaced apart from each other to form a vertical guide-way for a lifting-bar, and each part having a rack formed in its outer face, and a vertical slot extending through .said part from top to, bottom, the two slots registering with each other; a lifting bar adapted to move vertically in the guide-way and having an opening registering with said slots, and a series of lifts secured thereto; a main lever extending through said opening and slots and lpivoted to the lifting-bar; a pawl opposite each rack and adapted to engage therewith and pivoted to the main lever, and each be* ing adapted to span the slot and make e`ngagement with the rack on each side of the slot; and an extension spring secured at opposite ends to the respective pawls, and extending through said opening and slots.

3. The combination of two rac-ks faced away from each other in opposite directions with a guide-way therebetween, and with a vertical centrally disposed slot in each rack, the slots registering with each other,

a lifting-bar provided with an opening re l tending to force the pawls into engagement with the respective racks, a rock-shaft pivoted in one of said pawls and provided with en operating lever, a rook-arm secured to said shaft, and a link extending through said opening and said slots and pivoted to said rook-arm and having one-Way engagement with seid other p'awl whereby the operation of said link in one way frees said other pawl from the rack and whereby seid pawl is normally free of said link to pass over the teeth of the rack.

4. In a lifting-jaek, the combination with e standard having oppositely faced racks and a guide-way, a lifting-bar in the guideway, and a mein lever and two pawls engaging in the respective racks for lifting said bar; of-a 'rock-arm pivoted to one of said pawls, a link Connecting said rock arm with the other pawl, and a lever for operating In testimony whereof I have affixed my i signature in presence of two witnesses.

WILLIAM F. RIGHTMIRE.

l/Vitnesses:

JEssIE M. CURTIS, R. L. THOMAS.

Copies of this patent may be ohtained for five cents each, by addressing the Commissioner of Patents, Washington, D. C. 

